The present invention is in the field of glass composition and particularly relates to a new family of glasses wherein tin, phosphorus, oxygen and fluorine are essential constituents.
Among the known families of non-oxide glasses are the so-called halide glasses, consisting of amorphous products of the fusion of crystalline halides such as BeF.sub.2, ZrF.sub.4 and ZnCl.sub.2. A description of the glass-forming characteristics observed in halide systems is provided by H. Rawson in "Inorganic Glass-Forming Systems", pp. 235-248, Academic Press, London, New York (1967).
As noted by Rawson, while BeF.sub.2 and ZnCl.sub.4 can form glasses alone, more complex glass compositions based on these and other fluoride glass-forming compounds have been developed for particular applications. Thus U.S. Pat. Nos. 2,466,507 and 2,466,509 to Sun and U.S. Pat. No. 2,466,506 to Sun and Callear disclose a number of multicomponent glass compositions based on BeF.sub.2 and/or AlF.sub.3 for use as optical glasses or the like.